A suicide attack Wednesday which struck at the heart of Syria’s security apparatus killed defense minister General Daoud Rajha and President Bashar al-Assad’s brother-in-law Assef Shawkat, state media said.

Syrian General Hassan Turkmani, a former defense minister and senior military official, died of wounds sustained in a bomb attack in Damascus, Hezbollah’s al-Manar television and a security source said. Hafez Makhlouf, head of the investigations at the Syrian Intelligence Agency died in the Damascus explosion, Al Arabiya reported citing Syrian sources.

The bombing, which for the first time in a 16-month anti-regime uprising managed to strike at Assad’s inner core, adds urgency to a U.N. Security Council debate on Syrian sanctions later on Wednesday, when a showdown between Western powers and Russia and China is expected.

Officials said the bomber struck as ministers and security officials were meeting at the heavily guarded National Security headquarters in Damascus.

President Assad appointed Fahd al-Freij as a new defense minister right after the explosion.

Five more of explosions were heard on Wednesday near the northwestern Damascus district of Muhajireen, close to the base of the Fourth Armored Division that is led by President Bashar al-Assad’s brother Maher, residents told Reuters.

It was not clear whether those forces were being targeted.

Interior minister Mohammed al-Shaar and General Hisham Ikhtiyar, head of National Security, were among those listed as wounded in the first bombing, which came on the fourth day of an offensive launched by rebels to capture Damascus.

Severe blow to the Syrian regime

The Syrian Observatory for Human Rights called Shawkat’s death “a severe blow to the Syrian regime since he played the main role in operations by regular forces to crush the revolution.”

The Damascus suicide bombing will speed the end of the uprising against Assad, the head of the opposition Syrian National Council said on Wednesday.

“This is the final phase. They will fall very soon,” Abdul Basset Seyda told Reuters in the Qatari capital Doha. “Today is a turning point in Syria's history. It will put more pressure on the regime and bring an end very soon, a matter of weeks or months.”

Syria’s army said after the bombing it would “continue fighting terrorism.”

“The terrorist act increases the armed forces' determination to clean the country of terrorist groups,” it said in a statement, according to AFP.

Rajha, a Christian, was defense minister, deputy army chief and deputy head of the Council of Ministers. Assad himself is overall commander of the military.

Shawkat was deputy defense minister and a former military intelligence chief.

The National Security branch -- a linchpin of Syria’'s security apparatus -- is headed by General Hisham Ikhtiyar, who was also wounded in Wednesday’s blast, according to AFP.

The brazen attack on regime insiders came as battles raged across Damascus and after the Free Syrian Army (FSA) -- comprising defected soldiers and civilians who have taken up arms against Assad's forces -- warned the government to “expect surprises.”

Columns of black smoke rose over the capital, with the Local Coordination Committees, which organizes anti-regime protests on the ground, reporting that Qaboon and Barzeh neighborhoods were bombarded by loyalist forces.

It also said there was less traffic than normal in the city where fighting has raged since Sunday, with the rebels announcing a full-scale offensive dubbed “the Damascus volcano and earthquakes of Syria.”

Death toll mounts amid ongoing clashes

Regime forces and the FSA clashed in the al-Midan and Zahira districts of Damascus as well as at Assali south of the city, the LCC said.

As many as 114 people have been killed by the Syrian forces across the country, Al Arabiya reported citing activists at the Local Coordination Committees.

Fifty members of the Syrian special forces in al-Qaboun in Damascus have defected, sources told Al Arabiya.

Rebel forces on Tuesday said the battle to “liberate” Damascus had begun, as heavy fighting raged with the regime using helicopter gunships in the capital for the first time.

As the fighting inched closer to the regime’s nerve center, FSA spokesman Colonel Kassem Saadeddine said “victory is nigh” and the struggle would go on until the city was conquered.

“We have transferred the battle from Damascus province to the capital. We have a clear plan to control the whole of Damascus. We only have light weapons, but it's enough.”

“Expect surprises,” Saadeddine added.

Russia gave notice that it would not back a Western-backed U.N. resolution on the crisis as it would mean taking sides with a revolutionary movement.

“A decisive battle is in progress in Syria. Adopting the resolution would mean outright support of a revolutionary movement,” Foreign Minister Sergei Lavrov said in Moscow.

British Foreign Secretary William Hague said by contrast that Syria is tipping into chaos and collapse, and that a strong U.N. Security Council stand is needed to push for the creation of a transition government.

“It is clear that the situation is deteriorating rapidly,” Hague told reporters during a visit to Lithuania.

“The intensity of fighting is increasing, there are of course many reports now of fighting every night in Damascus itself, and this is reflected in the increasing flow of refugees,” he added.

In Beijing, U.N. chief Ban Ki-moon urged the Security Council to act to stop the bloodshed in Syria, after holding talks with Chinese leaders hours ahead of a vote on fresh sanctions.

Ban said the Security Council must unite and take action on the “very serious” situation in Syria, after meetings with China’s President Hu Jintao and Foreign Minister Yang Jiechi.

The Security Council postponed a vote that was scheduled on Wednesday on a Western resolution renewing the U.N. mission in the country that calls for sanctions if the regime does not pull back heavy weapons.

China has twice joined Moscow during the 16-month conflict to block resolutions critical of Damascus.

Ban has already urged China to use its influence to back a peace plan by U.N.-Arab League envoy Kofi Annan, who is calling on the Security Council to order "consequences" for any failure to carry out his six-point plan.

But China has repeatedly warned against outside intervention in Syria.

Representatives of the Syrian National Council (SNC) -- an umbrella opposition group -- met ambassadors from the 15-nation Security Council, including Russian envoy Vitaly Churkin, to press them to back sanctions.

The current 90-day U.N. mission in Syria ends on Friday and if no resolution is passed by then, it would have to shut down this weekend, diplomats say.

The Observatory, meanwhile, said at least 93 people were killed nationwide on Tuesday, among them 48 civilians, adding to its toll of more than 17,000 dead since the revolt erupted in March last year.